Telephone exchange



F A. LUNDQUIST TELEPHONE EXCHANGE Filed Aug. 5, 1904 g sheets-sheet 1 2 fi l'l'l'l l'l' fimk a x BY W Aug. 25, 1925.

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1,551,199 F. A. LUNDQUIST TELEPHONE EXCHANGE Filed Aug, 5, 1904 9 Sheets-Sheet 2 INYE-NTOR BY W06.

ATTORNEY.

WITNESSES:

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7 F. A. LUNDQUIST TELEPHONE EXCHANGE Fi1eam s, 1904 9 Sheets-Sheet 4 ATTORNEY.

Aug. 25, 1925. 1,551,199

F. A. LUNDQUIST TELEPHONE EXCHANGE Filed Aug. 5, 1904 9 sheets-sheet s INVENTOR'.

WITNESSES, p

foam/6 62, Q Q -q MM- o M da. ATTORNEY Aug. 25, 1925. 1,551,199

F. A. LUNDQUIST TELEPHONE EXCHANGE Filed Aug. 5, 1904 9 Sheets-Sheet 6 I INVENTOR: N G EfL gown/l6 a. I gwMej- M RTTQRN Aug. 25, 1925. 1,551,199

- F. A. LUNDQUIST TELEPHONE EXCHANGE Filed Aug- 1904 9 Sheets-Sheet I INVENTOR} RTTO KNE- Y.

Aug. 25, 1925.

F. A. LUNDQUIST TELEPHONE EXCHANGE Filed Aug. 5, 1904 9 s s a ooooqooooo 0000000000 0000000000 Fig.8

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Aug. 25, 1925.

1904 9 Sheets-Sheet 9 FTQZ .w-ijtucssa' Lu-ad 4 Patented Aug. 25, 1925.

UNITED STATES PATENT OFFICE.

FRANK A. LUNDQUIST, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A. CORPORATION OF NEW YORK.

TELEPHONE EXCHANGE.

Applicationfiled August 5, 1904. 'seri'ai. n 210,603.

To all whom it may concern: v v Be it known that I, FRANK A. LUND- QUISI, a citizen of the United States of America, and aresident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Telephone Exchanges, of which the following is a specification.

My invention relates to telephone exchanges, and more particularly to the arrangement of central office devices for automatically connecting together two subscribers when the total number-of subscribers rises to large numbers. The object of the present invention'is an extension and an elaboration ofthe system set forth in my Patent No. 747,197, issued Dec. 1 5-, 1908, in my Patent. No. 776,524, issued December 6, 1904, and my Patent No. 1,369,288, issued February 22, 1921.. The said application is very similar to Patent No. 776,524 but has its auxiliary switches interconnected by groups, as will hereinafter beexplained.

In an exchange system made according to the present invention there are three kinds of switching mechanisms which I designate as main switches, auxiliary switches, and intermediate switches. of switches do not need to be of any particular construction but each performs certain functions peculiar to itself.

As the details of construction of these switching mechanisms do not form a part of the present application they are shown in the drawings only in diagrammatic form. I will say, however, that it is not essential to the operation of an exchange of this character that the switches 'used should embody mechanical construction of an unknown kind. In giving a general description of the switching mechanisms, I will therefore as sume that each mechanical operation set forth is performed in the simplest possible manner. 1 A

In the accompanying drawings,

, Figs. 1, 2, and 3, taken together, show two switches of each kind and form a diagram showing how they are connected together.

Figs. 4, 5, 6 and 7, taken together form a general diagram showing the arrangement on line ll-ll of Fig. 8, of the erated by magnet C.

Fig. 12 is an elevation of one of the aux- A scribers, said diagram being abridged with 2 instead of10 taken as a basis.

Fig. 8 is an elevation of one of the main switches; y i

.Fig. 9is a section on line 9-9 of Fig. 8; Fig. 10is asection on line 1010 of Fig. 8; Fig. 11. is a somewhauenlarged section,

springs opiliary switches; and

Fig..13 is a rear view of some contacts located on the back of the auxiliary switch frame;

. In arranging 10,000 subscriber exchange of this kind, there is amain switch for each subscriben: These switches are divided into primary groups of 100, and secondary groupsof 1,000, each secondary group consisting of ten";- primary group. In case there were more a number of, secondary groups. This is on the assumption that 10,,the basisofour systemof notation,:is also thebasis onwhich These three kinds the grouping is made. Any other number mightbe .takenasthe basis. These mam SWltChGS, arev shown in F 1g. '1 and 111 the lower part of the general diagram. The,

whole number of main switches may be called a set.

The auxiliary switches are shown in Fig.

3 and in the upper part of. the general diagram. They are normally taken as ten per n than 10,000 subscribers, :and upto 100,000 subscribers, then there wo.uld be'tertiarygro'ups each made up of group, and 1000 in each tertiary group when such groups are used. The first primary group of auxiliary switches as used for making. connections to the different switches in the first primary group of main switches. In like manner the second group of auxiliaryswitches is for connections to the second group of main switches, and so on. The whole number of.auxiliary switches mayalso be called a set.

any main switch to any desired primary group of auxiliary switches. There are one or more'sets of these intermediate switches according to the number of main switches in the exchange. Thus, when there are from 1,000

to 10,000 main switches there is one set of intermediate switches. VVhenthere are from 1 0,000 to 100,000 main switches there are two sets or intermediate switches.

The presentapplication shows only one set of suchintermediate switches, though it I will bereadily understood that a second set might be inserted between the present set andvthe auxiliary switches. Such second set 'wouldbe madeup of intermediate switches precisely like the first set and differing in the same way "from both the main and auxiliary switches. v

Referring to Figs. to 7, each sheet represents a primary .group of main, intermediate and auxiliary switches. The switches on Figs. 4 and 5 taken together represent a secondary group of each kind, and Figs. Hand 7 represent anothersecondary group or each kind. "The'first primary group of intermediate switches is adapted to receive connections from any one ofthe 1,00 0 main switchesin "the first secondary group,and to extend those connections to the first secondary group of auxiliary switches. The second pl'l lnaly glOup of intermediate switches recelves connections from the same main switches but extends them to the. second secondary groupof auxiliary switches, and so on. f v V This matter may be stated in another way. 'llhe intermediate switches in any secondary group are arranged to receive connections from any main switch in the corresponding secondary group of main switches. Assumli g any secondary group of intermediate switches, any switch in the first primary group of such secondary group can extend a received conn e'ction'toone of the switches in the firstsecondary group ofauxiliary switches. The secondprimary group of interme'diate switches can extend connections to some switch in the second secondary group of auxiliary switches.

Instead of the first primary group of intermediate switches extending the connections to the firstsecondary group of auxiliary switches, and the second primary group of intermediates extending to the second secondary group of auxiliaries; the first primary group or intermediate switches may extend the connection to the "first-primary group of each secondary group of auxiliary switches, and the second primary group of intermediates may extend to the second primary group or each secondary group of auxiliary switches. This difierencc is a mere detail that involves nothing more than precedence in the order of selecting primary or secondary groups of main switches.

in operation the subscriber operates his connected main switch so as to make a preliminary selection of a desired primary group of intermediate switches. As his main switch can-men only the 100 switches in the corresponding group of intermediate switches, his preliminary selection is of a definite group of ten switches. He then starts his main switch into automatic operation causing it to move into successive connection with the dillerent switches of this preliminarily selected grou As soon as the main switch reaches connection to an intern'iediate switch which is not in use and which is consequently in its normal position, his main switch automatically stops and the selected intermediate switch is automatically moved away from its normal position. The selected intermediate switch is thereby transferred from the unemployed to the employed class and cannot be reached by any other main switch until after it has been returned to its normal position.

It the snbscribers preliminary selection just described had been for the second primary group of the associated secondary group, then the finally selected intermediate could connect to any switch in the second group of auxiliary switches.

The subscriber then operates the selected intermediate switch soas to make a preliminary selection of a desired primary group of auxiliary switches, and starts the intermediate switch'into automatic operation. In the same maiiner as previously described, the intermediate selects an idle auxiliary switch and removes it to the employed class. The selected auxiliary switch may then be moved to connection with any one of the main switches thatare located in the corresponding primary group.

'The main switches best adapted for exchangesot the kind here described each have two groups of contact points. Each group has 100 contact points arranged inten rows of ten points each. Co responding contact points in the two groups call a pair of contact points. Thus, the first contact point of the first row of one group, and the first contact point of the first row of the other group constitute a pair.

There is a contact maker, usually called a wiper for each group or contact points. These wipers are mounted upon a carriage, but insulated from each other, and the carria'ge'is movable laterally so 'a sfto bring the wipers adjacent'to successive rows of contact points. The carriage is also movable vertically so as to carry the Wipers over the rows of contact points which are adjacent to them at the time of beginning the vertical movement.

Each switch is provided with a series of magnets for performing the mechanical op erations and for closing contacts as will be hereinafter described. In the drawings, those magnets whichhave mechanical work to perform are shown of relatively large size, while those which simply close contacts are shown of relatively small size. Thus'the magnet A is the one used for moving the wipers laterally while the magnet a is simply a relay for closing the connections for A. In the same way, B is the magnet for moving the wipers vertically while 5 is a relay for B. 'As the mechanical connections for causing such movements do not necessarily. involve any special or ,unknown constructions they are not shown, but are assumed to be made in any of the simele and well known wa s.

The magnet B has its arn'iature arranged so as to make and break itsown electrical connections. A construction for this is shown, though any other convenient form mightbeusedQ v A magnet C has a hook 0 connected to its armature lever, which hook catches over a contact spring when the armature is at-.

tracted and which makes and breaks a series of electrical connectionswhenthe arn'iature is released. A spring connected to thearmature lever furnishes the power for operating these electrical connections. Although this magnet is. a contact closing magnet it has some work toper'form and is consequently shown of intermediate size. 1

There is also a magnet J used to release the carriage that carries the wipers from its propelling magnets A andB so that the said wipers may fall back to their normal position. The mechanical connections for this may be of any of the well known forms.

The carriage has a projection upon it which, when at its lowest position, opens connection between springs 32 and 33. Also on thecarriage is a contact maker 16 which is normally disconnected from a contact strip 15, but makes connection therewith upon the first lateral movement, which connection is broken upon the first upward movement. In falling back to its normal positiomthe carriage strikes a tail upon the hook c and releases it after it has been operated by the magnet C. For convenience, I have marked by the character M detached portions of the carriage that effect such mechanical operations. There are also certain other contactsmade 'and'broken by the mowinents of the carriage: which will be frame to which are securedthe parts for ing the switch mechanism; Near the upper part of this frame is a block of insulation 301 which carries the two groups of contact points and also the contact strips 15, 158, 165 and 166. On the frame 300 are lugs 302 which carry the parallel rods 303, and on these rods is the vertically movable carriage M. Secured to the slide M is a ratchet bar M suitably guided by a slot M in said bar and a pin 304 in the frame 300. Magnet B operating through its armature 305 and pawl 306 serves to move the carriage M up ward step by step. A holding pawl 307 prevents a return of the carriage to normal position until released. In normal position of the switch a hook on the-armature 305 engages a hook on the pawl 307 and holds'that pawl from engagement with the ratchet M but upon thefirst operation of the magnet B these hooks are disengaged and the pawl 307 engages the ratchet M Secured to the armature of the release magnet J is a hook 308 which extends adjacent to a projection on the pawl 307. i If the magnet J is actuated after thecarriage has been advanced.

and the pawl 307 is in engagement with the ratchet M the hook 308 will engage the pro jection of said'pawl. Upon breaking the circuit for an actuating impulse through the. magnet J the return of the armature and the connected hook 308 serves torelease the pawl 307 from the ratchet M and also to throw the hook on said pawl behind the hook on the armature lever 305 of magnet B'. 3 1

This permits the ratchet M and carriage M to fall by gravity to their lowest ornoi ma-l position, which lowest position is determined by the lower lugs 302 on the frame 300.

Inthe carriage M is a slide M which carries the insulated wipers or contact makers 16, 43 and 69, and also mounted on suitable posts on this slide is a ratchet bar Mt.

At a suitable position'on the'lirame 300is a magnet A whose armature lever 309 carries a pawl 310 adapted to engage the ratchet M to move the slide M laterally each time the magnet A isactuated'. A holding pawl 31]. pivoted on the carriage M serves to'prevent backward movement of: the slide. M

l/Vhen the mechanism is in its normal posi- 'tion this pawl 311 is out of engagement with the ratchet M by reason of its heavy tail end resting upon the end of a spring 312 which is supported on the frame.

Secured on the lever 309 is a rod 313, the other end of which carries a collar adapted to engage the spring 312. hen the mag net A. is actuated to advance the slide M the collar on the rod 313 strikes the spring 312 and pushes it from under the pawl 311. hen the carriage has been moved upward one step, the pawl 311 is lifted far enough for the spring 312 to come again under the tail of pawl 311 so that a drop ping of the carriage results in releasing the holding pawl 311. A coil spring 314 which runs over a roll 315 and has one end secured to the frame 300 and the other end to a post 'on the slide M serves to return the slide to its normal position when released. The other elements of the main switches will be apparent from inspection of the drawings and from thefurther description connected with the operation.

The intermediate switches are very largely made up of the same elements, though they have more connections at some placesyand less at others. They will be readily understood by comparing them with the foregoing description and what appears hereinafter. The magnets A B etc., of the intermediate switches correspond to the magnets A, B, etc. of the main switches.

The auxiliary switches have a good many of the characteristics of themain switches but differ therefrom in many other respects. Each one has three groups of contact points and each group has a. corresponding wiper. These wipers are correspondingly :moved by means of the corresponding magnets A and B There are also four other wipers mounted upon a shaft but insulated from each other. Magnets E and F operate this shaft through a ratchet wheel as shown and as will be hereinafter described, and cause these wipers to be moved over contact points. Other features of the auxiliary switches will be set forth in connection with the operation.

The auxiliary switch is illustrated in Figs. 12 and 13, and in many respects is like the main switch. For convenience, those parts of the mechanism which are substantially the same are given the same reference characters. The parts operated by the magnets A B and J are in all essentials the same as those described in connection with magnets A, B and J of the main switch and need no further description.

On-a spindle-N is aratchet wheel N having teeth out only on a portion of its periphery. hen the magnet E attracts its armature 315 the pawl 316 releases the holding pawl 318 from catch on lever 322, and engages a tooth in the wheel N I When the mag-net releases its armature the spring 317 causes-the pawl 316 to move the wheel one step. The'holding pawl engages the first adjacent notch and holds the wheel from returning until released. The magnet E can advance the wheel only three steps because there are only three adjacent notches in the wheel. As there are only three notches adjacent to the holding pawl 318, that pawl can hold for only three steps. At the end of three steps another notch 319 is adjacent to a pawl 320 on the armature 321 of the magnet F. In this position an actuation of the magnet F serves to advance the wheel N another step, but as the holding pawl 318 does not operate beyond three steps a release of the armature 321 permits the wheel N to return to the three-step position.

On the lower end of the ratchet'bar M is pivoted a bell-crank lever 322, one arm of which is on one side of the bar and the other arm of which is on the other side.

The vertical arm of the lever 322 has a hook on its end which is adapted to-engage a tail on the holding pawl 318 and release that pawl from the wheel N when the carriage of the auxiliary switch returns to its normal position. 7

A spring shown in dottedlines under the wheel N of Fig. 12 serves to return the wheel N and its spindle N to normal ;posi tion. The spindle N runs through the frame of the machine and on its other end carries four insulated contact makers 97, 114, 126

and 141.

Adjacent to these contact makers are insulated contact points arranged as shown in Fig. 13, which figure shows the contact makers in normal. position. When the ratchet wheel N 'is advanced step by stepv as previously described, the contact makers are advanced step by step over their adjacent contact points.

In its normal position the lower end of the bar 'M engages a pin-on a. pawl or'catch 324 and holds said catch clear of the armature lever 323 of the magnet L.

When the carriage moves upward one step the catch drops into a position suitable for engaging and holding the lever 323 in its moved position when actuated'by the magnet L.

When the carriage again drops to its normal position, it releases the catch 324 and permits armature 323 to return to its normal position. The armature 323 controls certain contact springs as will be hereinafter described.

In arranging an exchange all of the main switches located in one secondary group are connected to a bank of wires, there being as many wires in 'a bank as there are contact pointson'one switch. -Ordinarily there are pairs of contact, points on a switch and hence there would be. 100 pairs of wires in the bank andlOO intermediate switches connected to the bank. In some cases, it is desirable to have more than 100 intermediate switches to 1000 main switc11es,in which intermediate switches. As thus arranged, each secondary group of mam switches forms a unit that is not directly connected in any way with any of the other secondary groups. To make connection from one of these units to another, it is necessary to go through some one switch in the set of auxiliary switches. It will be observed that there areas many banks of wires as there are sec ondary groups of main switches and that each group, as a body, is connected to a corresponding bank of wires.

There are as many secondary groups of intermediate switches as there are secondary groups of main switches, and these secondary groups of intermediate switches are connected to an equal number of banks of wires. These last connections are not, however, from a secondary group as a whole to a bank as a whole as is the case with the main switches.

contact points connected to the first bank, the second group of each unit has its con tact points connectedto the second bank, and so on. As before. stated, the ordinary number of intermediate switches in a primary group is 10, and the number in a secondary group is 100. When thenumber of intermediate switches is increased, this in crease is obtained byadding switches to the primary groups and not by increasing the number of either the primary or secondary groups.

When the main switches have their vertical rows of contact points lengthened so that the number of intermediate switches in each primary group may be increased, the intermediate switches also usually have their vertical rows of contact points correspondingly lengthened so that the number of auxiliary switches in each primary group may also be increased. The object of this increase in the number of switches in the arimary groups of intermediate and auxiliaryswitches is toincrease the certainty of Considering each secondary group of lntermedlate switches as aunit, the first primary group of each unit has its the automatic upward. movement of :a main switch or an intermediate switchfinding unemployedswitch to which it can connect. Returning now to, the several banks of,

wires which are connected to the contact points of the intermediate switches, that bank which is connected to the'first primary group of each unit of intermediate switches is connected in turn to the first secondary group of auxiliary switches. That bank which is connected; to. thfisccond primary group of each unit or lntermed ate switches is connected to the second iary switches, and so on.

All of the contact pointsin thefirst pri: mary group of auxiliary switches are con group of auxilnected to a bank of wires that are in turn a In addition tothis, each primary groupof auxiliary switches has a special bank of wires 0t its own WlllCll speclalbank serves as means for interconnecting the third groups of contact points on these switches. These interconnections serve as a means for preventing interfering connectionsas will be hereinafter described. p

In. an exchange of the present character, there is a battery X, a generator G, a busy buzz or, interrupter W, some condensers in certain lines, and contacts and connections as shown. These various elements are connected up in the manner illustrated. For I each main switch there is a telephonestation T provided with two contact buttons marked 1st and 2nd. i i Referring to the diagram of Figs, 1, 2

and 3, it will be assumed that'the' subscriber located at the telephone shown at the left of Fig. 1 wishes to talk to the one located at the'telephone shown at the right of the same figure. It will also be assumed that the calling station is No. 1 and that the called station is No. 2, 112. In a system 01": this kind the figures that go to make up the numberot a station are themselves used to indicate how the subscriber is to operate in calling any other subscriber. means'that two contacts are to be made, 3 that three contacts are to be made, and so on.

In this system also,'tl1ere is one contact to Thus, 2

be made by a different contact making device between the times of making the con- .quence being that the subscriber does not.

have to regard it and is unconscious of its existence. As such a callingdevice is not a part of the present application, keys or contact buttons, as before mentioned, are

rture 5. omake connection to contact spring This operation of the magnet A moves the carriage'carrying the wipers 43 and 69 laterally ne step under the first row of contact points and causes contact maker 16, on a part of the carriage M, to engage strip 15 preliminary to an. upward movement. As the subscriber presses the button twice this operation is repeated and the wipers are. moved to a position under the second vertical row of contact points. To avoid confusion of lines, connections are shown. only from this second row of contact points to; the. bank wires though it is to be understood that there are alsov connections from the other contact points to similar wires in the same bank.

The subscriber then presses the 2nd key. once when a current flows :+XY1-1 14-1516'17-18+b-1920.T- ground-X. This causesthe armature 28' to connect to the spring 24 when a current flows X-1--1"2122-23.2425.'26 2728.B'2930'1011 1. 4 12 This causes the carriage carrying the wipers to move upward one step and carries'the contact spring 16 away from. the strip 15 so that no subsequent contact made by the 2nd key can send an impulse through magnet Z) and thereby again close the'contact for magnet B. This same upward movement carries another part of thecarriage M away from springs 32 and 33 so that they may come together and, close a new. circuit for the magnet B.

WVhen this occurs a current flows; X.- 1l 21-3132-33%34:35 36 3728 B+2Q30.10 ll 12 12 13 This again operates magnet B and moves the wipers upward another step.

The armature lever 88 of the magnet B has an arnfr that engages a fork on the pivoted lever 35. When the armature is attracted this arm throws the lever 35 off of the contact point 36 and thus breaks the,

circuit for B. Upon thus breaking the circuit through B, thearmature 38 returns to its normal position in the ordinary way and again causes 35 to engage 36. p This again operates the magnet. It will thus be seen that by this means the magnet B continues in perauon automatically making and breaking its own circuit.

This causes the wipers to move upward step step:overthe'selectedi row or contact The passingof a current through C causes the hook c' to catch on spring 30 and break the connection between 3,0, and 9. It also connects 10 to 150, 71 to 72, and 84 to S3.

The breaking of the connection between 30 and 10 breaks the circuit for the magnet 13, and hence stops the. upward movement of the carriage with its wipers in connection with the intermediate switch found in its normal. position.

The same current flowing through 6 causes 54 to contact with 55 when a current flows X1 1 ,-5253'-5 1 5556 57 5859B 60 616'2j631 12 12 13-X. The operation of the magnet B moves the carriage of the intermediate switch upward one step and carries" the part M away from the lever 49 so that that lever shifts from contact point I 50' to contact point 82. In the case of the intermediate switches, the part of the carriage which separates and 7 5*' is made long enough so that-it requires two upward steps to remove it. The reason for this is that the first step is, for isolating the switch, and 75' and 7.6 are required to be in connection during the lateral movement.

The breaking of the connectionat 50 cuts the. current from therelay b and causes a breaking in the circuit 01- B at 54- 55. As a consequence of this no other main swltch ,in moving to connection withthe bank wire 45 would" find this particular intermediate switch in a position in 'which it could send an impulse through the relay magnet 6 The next figure in the number of the station desired being 1 the subscriber presses ;g 'roundX. The operation of relay a closes. 81 to when a current flows.:X-1

and 6 for the magnet A. But as the magnet,

C had been previously operated the circuit for A had been broken at 80, hence this branch is without effect. I

The subscriber then presses the 2nd key once to start an automatic upward ground-X. This closes the circuit for B as before and causes another upward movement of the carriage. This causes 75 to close to 75 thus making a circuit for B the same. as was made for B ot the main switch. As the armature of B is provided with connection similar to those are, the

magnet B makes and breaks its own circuit and moves the carriage of the intermediate switch upward automatically step by step the same as described for themain'switch.

\Vhen the wipers of the moving interme-' diate switch reach connection to apair of contact points that are connected toan auxiliary switch whichis at the time in its normal position then a current flows:X-1 1 52-86878S C 89-+909192 93-9 1-95-b?-9697- 98 12- 12 13 The current through C operates that magnet to break the connection between springs 61 and 62, and also to operate the adjacent contact springs the same as described for the main switch. As the springs 61 and 62 are in the circuit for the magnet B it is evident that the operation of G stops the operation of B and consequently stops the upward movement of the carriage of theintermediate switch with its wipers on the contactpoints which are in the circuit described. p

The-same current through 19 closes 101 to 100 when a current flows X1199 1OO1O1 1 O2E98 1 2 12 13 X; The current through E attracts its armature and causes the pawl thereon to engage and turn; the ratchet wheel N and the shaft N. This moves all of the wipers on this shaft from their normal position one step forward and consequently breaks the circuit for the I relay 5? between 97 and the terminal of the line 98. The operation of the ratchet wheel N is shown in Fig. 3, for the convenience of the diagram, as being made'by the armature of Ewhilebeing attracted. In practical operation, however, it is made by the release movement of the armature in Fig. 12, the object being to prevent a premature breaking of the circuit for 5 Itwill be observed that in this case the relay 5 does not close connection for the magnet Bflbut for another magnetlE'which magnet, as will be hereinafter described, finally closes connection for B through another wiper on the shaft N. r

The next figure of the desired station being 1 the subscriber presses 1st key once when a current flows: X1"1103-- a 10t105106-107--l O8 109 110 1.1 1--6 6-676 8*69 7172?3 "4t T- -groundX. This closesllS to 117 when a current flows X-1l-99112- 113 114l-115-A l16-117-11S 119 98 12i2-13 -1. This moves the wipersto a position under the required rows of contactsf If the figure in the number for the desired station had been greater than 1 then the key would have been pressed a correspondlng number of times.

The 2nd key is then pressed once when E a current-flows: X- -1-l-991l2113 20eT-groundX. This again closes the circuit for the magnet E causing an otheradvance of the wipers on shaft N. Inthis posltion the wiper 114iis on the terminal of the wire leading to magnet 13?.

The next figure being 2 the subscriber pressesilst. key twice. ThIS closes circuit throu h a the same as before. This time the contact between the armature 1 18 and the spring 117 closes the circuit for B be} cause of the position of the wiper 114- and the current is the same as previouslyde scribed for A except for-the. substituted link a between 11a and 116. Thisbeing repeated carriesthewipers onthecarriage upward to the desired pair of contactpoints. In this position these wipers have completed the electrical connectionbetween the calling sta tionandthe one'wanted. 1 p a Thesubscriber now presses 2nd? key once closing connections for b and E the \same as before thus causing shaftN to be advanced one morenstep toibrrng wiper 114 into electr cal connection with the magnetv F. In this position the upper two wipersf on the same shaft rest o'n the next to the last of their contact, points, which contact points are inl the,talkingcircuit; This is the ex-' treme position to which the magnet E can advance the-wipers on the shaft N, and the extreme position at which the holding pawl for the wheel N can maintain them. i The A and B except that this time it goes from i 114 to 116 bythe way otF. This advances temporarily the wipers ontheshaft N, the last, contact for wiper 11 1 beingof extra In the circuit T is an arbitrary for the telephone station at which there is presumed tobe located the ordinary telephoning set including receiver,- transmitter, induction coil, and battery arranged in the ordinary manner. 7

This talking circuit consists of two metallic connections between the two telephones, in which connections there no resistance other than that of the line itself. Between one of these line connections of the above circuit and the battery connections 1*, 1

and 1 there are bridged three magnets, b of the intermediate switch, 12 of the auxiliary switch, and a of the called switch.

Between the other line and the same bat tery' connections are also bridged three magnets, a, a and a These magnets are made with equal resistances", and there being the same number on each branch the line is balanced v When through talking the subscriber at the calling station presses both keys simultaneou'sly but begins with the 1st key a little in advance of the 2nd key.

In calling devices of the kind usually used in automatic exchanges, operations of this kind are ordinarily performed automatically by a descent of the receiver hook when hanging up the receiver. The various circuits resulting from this permit impulses to pass, as will be described, for releasing the moved switches and permitting them to return to their normal positions. In this con nection it is proper to note that the talking circuit just described has condensers in it, which condensers serve to stop a battery current and thusprevent the currents now to be described from going the wrong way.-

108:109--110-y111-66 etc. This circuit with its three branches through the relays a, a and a operates them and causes their respective armatures to make connections to branch 1-99112-1139796-b?95 949392- 91; 90 121 122 46-etc. This circuit with its three branches through the relays b, 12 and operates them and causes their respective armatures to make connections with the adjacent contact springs. 1

The operation of the relay a closed the circuit just described for b, and upon the operation of b a current flows; X1-1 2122'94314L7 '1 18-J- 149 ,15010- 1112" 1213X.

The operation of'the relays a and 6 close the circuit for the magnet J of the intermediate switch when the current flows: X-1- 1 52-5 354e-151 152-J -79'80-8"1 -6-312 12'-13-X. v

The operation of the relay 6 closes the circuit for the magnet E when a current flows: X-1-1+99100-101-102-E'- 98-121213*X. Then the operation of a and E close the circuit for the magnet J when a current flows: X1199-112 -153'154.'155J 156 157 118-119 -98-1212*-13X.

'lhemagnets \L-J andJ are themagnets used for releasing their severalswitches from their propelling magnets, which release may be mechanically eifected in any of the well known ways.

For practical reasons relating tothe times of breaking circuitsthe actual release does not occur upon the actuation of the release magnets, but upon the return of their respective armatures to their normal positions.

Upon each release the switches fall back to their normal positions either under the force otgravity or the force of springs.

In the main switchsome convenient part inreturning to normal position strikes the rear end of the catch 0 and releases said catch from the spring 30, thereby permitting the other adjacent springs to resume their normal positions. Another part separates the springs 32 and 33. The same operations are performed in the same way by the return movement of the intermediate switch, and in addition thereto the carriage moves lever 49 from contact point 82 to contact point 50. The auxiliary switch releases the holding pawl for the ratchet wheel N and a catch associated with magnet L, provided that magnet has been operated as will be hereinafter described; .7

Returning now to the automatic upward movement of the main switch it will be re-' membered that this upward movement con tinued until the wipers carried thereby come into connection with an idle intermediateswitch, when the main switch stops. In case the wipers should pass over the entire vertical row of contact points without finding any idle intermediate switch then the wipers will passover the strips 165 and 166 and wiper 13 will make a temporary connection with strip 158. Then a current flows:

it is shown as the direct result of operating the magnet G which breaks the circuitfor B, at the spring 30. l

As soon as the wipers assume the position described a current flows: VV160-161 162163. 1 T20-S58d+834:243166+167- l68-169170,-17l--W busy buzz.back to the calling telephone whereupon the calling subscriber releases his switch as previously described. I

The intermediate switches are provided with thesame kind of strips connected in thesaine way to the buzzer, and the consequence is that in case the main switch finds an idle intermediate switch but the intermediate fails to find an idle auxiliary switch, then a busy buzz is sent back in the same way to the calling station.

In the case of the auxiliary switches the system of sending back a busy signal is different. In this case each auxiliary switch is provided with an extra wiper and a corresponding group of contact points. "It also has a magnet L for closing connections to thebuzzer 1V. This difference arises from the fact that in the first two cases thebusy signal is sent back because an idle switch is not found, while in the third case the busy signal is sent back because two different subscribers havemoved two different auxiliary switches to electrical connection with the main switch of some one subscriber.

Fortwo auxiliary switches to move to connection with the same main switch, both auxiliary switches must have their wipers in corresponding positions, and both must be long to the same primary group.

Assuming that both of the auxiliary switches of Fig. 3 had moved to electrical This throws a connection to the switch of station No. 2,112,

then a current will flow 112L-17 2- 17 8 174l- 175- 176-? 177- 178*177 of the other auxiliary switch l76175.l7d 98-1212 13-X. This is on the assumption that the auxiliary switch at the right of Fig. 3 was first in connection with thedesired station and that the one at'the left is the one moving to a a connection already established. The circuit just described is not completed simply by virtue of the second auxiliary switch mov ing to apreviously established connection, but is completed only when the subscriber having stopped his auxiliary switch at an interfering connection closes the connection shaft N to their extreme position.

The magne' connections of any of the well known kinds for releasing the pawls operating upon the. ratchet wheel N described therefore. causes arelease of the shaft N from its propelling and holding devices and permits said shaft and the wipers thereon to return to normal position. At-

tracting the armature of the magnet L by reasonof this current closes 181 to 182 and 184C to 185. A hook adjacent to the armature holds these connections closed after. the circuit through L s broken, and until,

the carriage of the auxiliary switch is re leased and returns to its normal position. r

lVhile these contacts remain closed a cur-c rent flows: W179180-181182 105l0G107108-109+-1-10 111- 66- The operation of the magnet L caused by closing the circuit last for the magnet E to move the wipers on the t L is provided with suitable signal back into the calling telephone and indicates thatthe desired party is busy. 7

The case just described assumes that the subscriber at station No. 2,112 had been called by some third party, and'hen'cethat the switch of the called station was at its normal position. j V

In case the subscriber at the desired station hadycalled and was talkingto' some third party, then his switch would be away.

from its normal position and the springs 132 and 135 would be moved away from contact points 133 and 13 4, and into connection with contact points 188 and 189.

As the contact points 133 and 13 1 are in the s talking circuit ofa called station telephonic connections cannot be madeto a switch that has moved, and as the contact points 188 and 189 are connected by wires 190 and 191 .to the previously mentioned buzzer circuit an attempt to connect to a moved switch sends a busy signal back to the calling station.

tions Reviewing "briefly, what has been "hereto" fore said'it "will be seen that thesubscriber makes at his station, numbers of contacts that are indicated to him'by the-number of thestation he wishes to call. Also that after making the contacts "for any number he makes one additional contact that sends an impulse over a line different from that which carried the impulsesrepresenting figures in the number for the desired station.

Ordinarily'this extra contact is made au tomatically by the calling device used, a con venient one of which is shownin; my Patent No. 822,965, issued June 12, 1906. V

The switchingjmechani'sms'fare operated from a batteryfbyiconnectionsi closedby'f keys at the station "or by a suitable calling device. Each, switch carries two insulated wipers which itjiirst' moves in one direction an then in a'di're'ction perpendicularthere to,'and a sesover contact? points which are connected to other switching mechanisms. Theseothe'r' "switching mechanisms have a" connection'to the battery when "they are "in their normal positions, but when'a switch moves its normal connection to the battery is broken and a new one, through another line, is substituted therefor.

The insulated wipers 'j us't' referred to are not normally connected to the battery, but" one of themhas such "a connection"temporarily'made at each forward movement over its Contact points." This temporary'connection) and the" normal connections of-"the switches (those connecte'd'to these" contact points) to'the battery. are 'suchthat when this wiper touches a contactpoint -whose switch is in normal position, an"impulse flows through that switch and this wiper and causes that particular switch to be moved from itsnorinal position, As "the new connection to {the battery :or the switch thus automatically moved doesjfnot involve the same branch to the battery through which the temporary circuit was made the switch is no longer-in the'same kind of an operative connection to this Contact point. 7

It will be observed that the'curreiit which" flows throiigli the win-eras cause: an aiito'-' mati'oiselecti' o'n of a switch wliicli is at "theitime in its normal position "emanates from" the same battery which supplies 'tlie energy for moving thewipers. H

In this automatic selection of an'idle' switch it has been heretoforenecessary' to use an extraor auxiliary "battery to furnish the necessary energy. Thi is because, int-h circuits as heretofore arranged, 'combina ;of-'"m'ovein'ents of different switcheswoiild sonietimesisend impulses-which "would dear-range tlieaesirec systemtr movementsia By the' present arr'ai g iii-rent" this note not occur and I am consequentlyenabled' to dis-- pose of the extra battery and the neces sary connections therefor.

has sel'ected an auxiliary switch intlie man- It will be observed that the' 'wipers' era switch are not normally connected to the station, nor are they connected to the station during the time they are being moved. They are, however, both automatically connected to the station the instant that an idle switch is found by their movement. This connection'is establishe'd'by the operation of the magnet C, which magnet also stops the automatic movement of the switch. It will be noticed from this that this automatic connection of the wipers to the station is in reality an extension of the line from the station, and that a part of this extension (the wiper 43) is used to form the temporary circuit for finding an unemployed switch. Upon the completion of this extension the newly selected switch bears the same relationship to the calling station that theoriginally moved'switch bore at the time of its movement. The line simply extends from the station through'the first switch to the second switch.

Although'the wires 4 and 20 which extend from the station do not normally connect to the wipers, yet the wipers when at normal position connect these wires to the springs 132 and 135, and these springs are in turn connected'bywires 131 and 136 to some particularpairof wires in the bank of wires to'w'hich the members of some group of auxiliary'switches connect. These wires 131" and 136 are really extensions of the bank wires and may be called normal wires'of a station because, 'when'the main switch of a st-ationis at its normal position, these wires are connected directly to'the station. As

soon as the main switch moves away from its normal positlon its normal wires are automatically connected to the busy signaling device W by means'of the wires190' and191 the right hand portionof- 1. As--{'a conse uence of this,'- when some subscriber ner previously described and has moved that" auxiliary switch to the normal Wires of some other station, he either connects to that sta-' tion "or" to the busysignal according. tot whether"the-switch' of that station is at its nornii'al -p ositiori' or has been moved;

aswill be most-readily seen by inspecting By aerrnagrbaek td-fthe m'ain switch era cal-ling station; it' will be noticed "that"the wipers are notconnected' to the lines run ning tothe-station until the switch move- -ments have been stopped. If this stoppage occurs before the switch reaches its "extreme position'the connection of the station is to some other switch; but if the stoppage'is only; at the extreme position, then the 'con' neo'tions' intended *for a talking circuit ex tend directly to the busy sighting" device In'the *same way, when 'aninterm'ediate switch has been selected and 'moved," the extended connections of the stations either t from each main ,consisting of a number of ---mediate switches to all o connect to some auxiliary switch or directly to the same busy 'signaling'device. And again, when the auxiliary switch is similarly moved the still further extended connections of the station connect to the normal wires of some other station and either reach that station or directly to the same busy signaling device.

It will be seen that in all of these operations the busy signaling device is connected directly to the lines intended for a talking circuit, and that no third wiper is required to accomplish the desired result. The only time that a third wiper is used is in that combination in which two auxiliary switches connect to the same pair of normal wires.

In applications previously filed by me, as in my. Patent No. 747,197, issued Dec. 15, 1903, and in my Patent No. 1,369,288, issued Feb. 22, 1921, interfering connections were prevented by breaking the line intended for a talking circuit thus leaving the calling station with open connections. In the present case interference or intended for a talking circuit but by shifting those connections directly to abusy signal device.

What I claim is 1. In a telephone exchange having a main switch for each station belonging to the exchange, a division or" such main switches into primary groups containing a number of switches and into secondary groups each ,a separate bank of wires for each secondary group of main switches, contact points on each main switch connected to the different wires of the bank of wires to which it belongs, a setof auxiliary switches less in number than the main switches and correspondingly divided into primary and secondary groups, a bank '01"- wires connecting contact points on the auxiliary switches of each primary group with the different switches in corresponding primary group of main switches, and a set of intermediate switches correspondingly divided into primary and secondary groups and provided with banks of wires and connections by p which telephonic connections may be extended from any main switch in any pri mary group to some auxiliary switch in some different primary group,

2. A set of main switches divided into primary and secondary groups, lesser sets of intermediate and auxiliary switches each of which is and secondary groups, electrical conductors group to all of the intermediate switches in a plurality of the primary groups of intermediate switches, other electrical conductors from each primary group of interthe auxiliary is not accom-' plished by breaking the connections used primary groups,

'tric'al connections of similarly divided into primary switch of each secondary switches in a pluralityof groups of auxiliary switches, and return conductors from each auxiliary switch of each primary group to all of themain switches located in a corresponding primary group of main.

. switches. V

3. In a telephone exchange, ,a plurality oi'sets of switches, a division of each set of switches into primary and secondary groups, and electrical connections so ar-- ranged that all of the individual switches of a secondary group of one set have the ary groups, and a set of final switches corresponding in number and intermediate switches, of connections from each primary group of main switches to a plurality of secondary groups of intermediateswitches not in the. same primary group, similar connections from each primary group of intermediate switches to a groupings to the plurality of secondary groups of final primary group,

switches not in the same and other connections from each secondary group of final switches to the correspond ing secondary group of main switches.

5. A switching mechanism provided with a pair of wipers through which a talking circuit is to be completed and said wipers adapted to be moved successively to the elecdifferent switches of a group of switches, a group of such switches, a telephone station provided with normally open connections to thewipers being moved, a magnetby the operation of which upon reaching connection to an idle switch in said group of switches said wipers will be automatically stopped and their normally open connections to said station will be closed, and means by which the circuit for said magnet is completed by one of said wipers.

6. A group of switches each. of which is provided with a pair oi electrical connections, a pair of wipers adapted to be moved successively to the electrical connections of group of switches each of which is 

